Bacteria in soil could provide electric power

On their own, the batteries don't provide much power, but they could be stacked to produce higher wattages.

ByRemy Melina, TechNewsDaily Staff WriterJune 11, 2010

Humans have harnessed wind power, hydropower, biofuel, and solar energy for creating electricity, but an overlooked renewable energy source could be right under our feet.

Using the small currents created by bacteria living in soil, a group of Harvard students was able to harness and collect that energy in a microbial fuel cell (MFC) for a class project. The most recent microbial-fueled battery can power a small LED lamp and can last for up to a year. Easy to make and simple to use, the battery costs $10 to $15 U.S. dollars.

"In the field, we have seen prototype 'batteries' no larger than a ten-liter jerry can generate enough power over time to charge LEDs, radios, and cell phones," one of the students involved in the project, Hugo Van Vuuren, told TechNewsDaily.

On their own, the batteries don't provide much power, but they could be stacked to produce higher wattages, the team says.

Literally making energy from dirt, the students successfully test-drove the MFC batteries in villages in Namibia, Africa, using soil and manure to fuel the batteries. Bacteria release energy when they metabolize dead leaves, compost and other organic waste. When an electrode, or electrical conductor like a copper wire, is added, the electrons attach to it, creating a chemical reaction resulting in a small charge of electricity.

The process of extracting energy from waste material is not a new concept. In fact, it was first discovered a hundred years ago by M. C. Potter, a professor of botany at the University of Durham, who was able to generate electricity from E. coli. British researcher H. Peter Bennetto further explored microbial fuel cell energy in the 1980s, recognizing it as a possible method of providing third world countries with electricity.

"The science is proven and tested, and there are many folks working to further MFCs," Van Vuuren said. "We are focused on taking them to the developing world."

Lebone's goal is to bring MFC technology to developing states in Africa, where 500 million people are without electricity. There, it can "passively harvest" energy from soil and waste, and create power in areas where it is scarce – or nonexistent - but badly needed. The team hopes to eventually make their invention available in the U.S.

Besides making energy out of something free and easily available, "dirt power," also referred to as "earth power," makes use of a renewable resource in a completely environmentally-friendly way. Lebone's aim is to ultimately expand the use of MFC off-the-grid lighting technologies in both developing and developed countries. Possible future uses being considered for the technology include outdoor lighting, remote sensors and deep sea devices.

"Microbial fuel cells are seeing more and more development, and scientists and engineers on the east and west coast and even in Queensland, Australia, are exploring ways to generate power for off-grid sensor arrays and to improve the production of clean water, to name a few areas of ongoing work," Van Vuuren said.